CN102007998B - Low-sugar Chinese chestnut preserved fruit and production method thereof - Google Patents

Abstract

The invention discloses the production method of low-sugar Chinese chestnut preserved fruit, which comprises the following steps of: inactivating enzyme by using microwave, performing acidolysis treatment and microwave-assisted vacuum sugar penetration, drying in sections, packaging and performing microwave sterilization. The low-sugar Chinese chestnut preserved fruit produced by the method comprises 40 to 50 mass percent of sugar and 12 to 15 mass percent of water, and has a golden color, gloss and the special fragrance of Chinese chestnut; the fragrance is strong; and the products have elasticity and certain flexibility and are not sticky. The special flavor of the Chinese chestnut is preserved; the low-sugar Chinese chestnut preserved fruit does not become hard and has toughness and good mouthfeel; and the products have low sugar content, long storage periods, high quality and broad market prospect, and are sanitary and convenient to eat. The related process can shorten sugar penetration time and improve production efficiency. Chinese chestnut resources can be fully utilized, Chinese chestnut products with high technological content and commodity value can be produced, and an effective way can be provided for the deep processing of the Chinese chestnut.

Description

A kind of low-sugar preserved chestnut and its production method

technical field

The invention belongs to the technical field of food processing, and in particular relates to a low-sugar preserved chestnut and a processing method thereof.

Background technique

Chestnut is one of the dried fruits with higher economic value. It is very nutritious and has certain health care effects. Its chestnut contains protein, carbohydrates, fat and other trace elements necessary for human body. China's chestnut production ranks first in the world, but due to the strong metabolism of fresh chestnuts, the short harvest period, and the limitation of storage and preservation technology, the development of the chestnut industry is seriously restricted, resulting in the loss of 35% to 50% of chestnuts in my country every year. At present, Chinese chestnuts are mostly sold as raw materials, and the processing of chestnuts is mainly rough processing. At present, the chestnut products on the market mainly include canned chestnuts in syrup, fried chestnuts in sugar, quick-frozen chestnut kernels, chestnut powder, etc. Generally speaking, there are not many varieties of chestnut products, the technological content is not high, the processing technology is relatively backward, and the market competitiveness is poor.

Preserved fruit is a unique traditional food in my country. It is a typical high-sugar product and has the characteristics of high sugar content, high sweetness, fullness and transparency, and long shelf life. With the improvement of people's living standards, consumption concepts have changed, consumers pay more attention to nutrition and health, and people are no longer interested in foods with high sugar content, resulting in the impact of traditional high-sugar preserved foods, and the export of foreign trade has also declined year by year. The light candied candy with a sugar content of about 55% and the low-sugar candied fruit with a sugar content of less than 50% have a strong original fruit flavor and a good taste, which will not cause people's psychological rebellion and are more easily accepted by consumers. At present, sucrose or high fructose syrup is commonly used as dipping sugar in the processing of low-sugar candied fruit, and there are few reports on the production of low-sugar preserved candied fruit with xylitol, which has certain health care functions. The sweetness of xylitol is 1.2 times that of sucrose, and it is accompanied by a slight cooling sensation after ingestion. It also contributes to the cleanliness of teeth to a certain extent, and has health care functions such as preventing dental caries and improving liver function. In addition, xylitol also has the advantages of good biological stability, good hygroscopicity, and no rise in blood sugar level after eating xylitol, making it more and more widely used in food.

During the processing of low-sugar chestnut preserves, most of the starch exists in gelatinized state, which will hinder the process of osmotic sugar in the process of preserved fruits. Moreover, the gelatinized starch is easy to age and retrograde, thereby affecting the mouthfeel, transparency and softening degree of the low-sugar preserved chestnut. And this low-sugar preserved fruit has the disadvantages of slow sugar infiltration speed, insufficient plump appearance, short storage period and the like due to reduced sugar content. Therefore, some auxiliary measures are needed to accelerate sugar penetration. For example, Zhou Lijuan and others have studied the use of amylase treatment technology to eliminate the hindrance of starch to sugar penetration and increase the sugar penetration rate of sugar solution. However, the time required for amylase treatment is long, the process is complicated, and the process is difficult to control. The obtained preserved chestnut fruit is relatively hard, with light yellow color and unattractive.

Since the 1990s, low-sugar preserved fruit has been actively researched at home and abroad. The processing technology, preservation, packaging materials and packaging forms of low-sugar candied fruit were systematically studied. For example, applying vacuum technology instead of traditional cooking process to process preserved fruit can significantly shorten the time of conserving sugar and improve the color and flavor of the product. In terms of color protection, foreign countries mainly adopt the method of sulfur fumigation to ensure the transparency and color of the processed low-sugar candied fruit. The SO ₂ content of the finished product is about 2000 mg/kg, which can make the low-sugar preserved candied transparent and have a longer shelf life. However, the presence of SO ₂ in preserved fruit will cause the color of preserved fruit to become lighter, produce an unpleasant SO ₂ smell, and lose the inherent fruit aroma and taste of preserved fruit, and the high concentration of SO ₂ in food will seriously damage the health of consumers. Residues are strictly controlled. The microwave heating speed is fast, the material is heated evenly inside and outside, and the action time is short. In recent years, it has been introduced into the processing of preserved fruit and candied fruit. For example, research by Ma Daorong et al. proved that microwaves can significantly promote sugar osmosis in apple tissues, and He Ren et al. proved that microwaves can rapidly increase the rate of sugar osmosis in fruit and vegetable tissues in a short period of time.

Contents of the invention

In order to solve the above-mentioned deficiencies in the prior art, the primary purpose of the present invention is to provide a processing method of low-sugar preserved chestnut.

Another object of the present invention is to provide the low-sugar preserved chestnut produced by the method.

The object of the present invention is achieved through the following technical solutions: a production method of low-sugar chestnut preserved fruit, comprising the following steps:

(1) Enzyme inactivation: heat chestnut kernels to inactivate enzymes, the purpose of which is to inhibit browning and improve production efficiency in the process of osmosis;

(2) Acid hydrolysis treatment: immerse the chestnut kernels after deactivation in the acid hydrolysis solution for 60-100 minutes at 70-95°C, then remove the chestnut kernels and rinse the remaining acid solution with clean water. The purpose of the acid hydrolysis treatment is to use hydrochloric acid to degrade the large-grained starch in the chestnut, loosen the structure of the chestnut, promote the subsequent penetration of the sugar solution, and prevent the aging of the starch and the decline in quality of the preserved chestnut during storage;

(3) Vacuum sugar osmosis: the chestnut kernel that step (2) obtains is immersed in the sugar solution and vacuum osmosis sugar;

(4) drying: pull out the chestnut kernel obtained in step (3), drain the sugar solution and dry;

(5) Sterilization: the chestnut kernel obtained in step (4) is sterilized to obtain low-sugar chestnut preserves.

The heating method for inactivating enzymes in the step (1) is to heat the chestnut kernels for 4-8 minutes under the condition of a microwave power density of 2-6 W/g chestnut kernels.

The chestnut kernels in the step (1) are complete, light yellow in color, free from insect damage and black spots.

The acid solution in the step (2) is a hydrochloric acid solution with a mass concentration of 0.5-1.5%, and 2-4 kg of the acid solution is needed for every kg of chestnut kernels.

The sugar liquid component in the described step (3) is sucrose, xylitol, fructose syrup, water, contains 13～18kg sucrose, 8～12kg xylitol, 21～28kg fructose syrup in every 100g water, wherein fructose The mass concentration of fructose in glucose syrup is 29.8%, and the soluble solid content is 71%. Every kg of chestnut kernel needs 1.5-3.5kg of sugar solution.

The vacuum osmosis method in the step (3) is microwave assisted vacuum osmosis, under the condition of microwave power density 3～4.5W/g chestnut kernel, vacuum degree 0.085～0.095MPa, immerse 100～150s, microwave Continue to infiltrate sugar for 50-70 minutes after the radiation stops. Microwave technology can maintain the original quality and flavor of food to the greatest extent. Due to its rapid heating effect, it will produce a puffing effect on food materials and form many pores, which will help increase the speed of sugar penetration and shorten the time of sugaring.

The drying method in the step (4) is segmental drying, first dry 12-18min under the condition of microwave power density of 2-4W/g chestnut kernel, then use 60-80°C hot air drying for 100-140min, and then Rapid cooling to below 40°C.

The sterilization method in the step (5) is microwave sterilization, under the condition of microwave power density 2.0-3.5W/g chestnut kernel, sterilize for 90-120s, and then rapidly cool to room temperature.

A low-sugar chestnut preserved fruit produced according to the above method, which has a sugar content of 40% to 50% and a moisture content of 12% to 15%, has a golden color and luster, and has a unique aroma of chestnut. The fragrance is strong and the product It is elastic, has a certain toughness, and is not sticky.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The invention uses acid hydrolysis technology to convert part of the starch into low-molecular sugars, which not only retains the unique flavor of chestnuts, but also does not harden, has toughness, and has good taste; xylitol is used to replace part of sucrose and fructose syrup to reduce sugar content. increase the cool taste of the product, and have a certain anti-caries effect; adopt microwave-assisted vacuum infiltration, microwave drying and microwave sterilization technology, which can shorten the time of sugar penetration, improve production efficiency, and the product has low sugar content and long storage period , good quality, hygienic and convenient to eat, and has a broad market prospect. The invention can make full use of chestnut resources, produce chestnut products with high-tech content and commercial value, and provide an effective way for deep processing of chestnuts.

Detailed ways

The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

Example 1:

(1) Raw material selection: thaw the frozen chestnut kernels, and select chestnut kernels that are complete, light yellow in color, free from pests and black spots.

(2) Microwave inactivation of enzymes: take the microwave power density of 2W/g chestnut kernels, heat the chestnut kernels for 8 minutes, and perform enzyme inactivation treatment.

(3) Acid hydrolysis treatment: According to the ratio of 2 kg of acid hydrolysis solution per kg of chestnut kernels, immerse the chestnut kernels in a hydrochloric acid solution with a concentration of 1.5% (mass fraction) at 70° C. for 80 minutes. Then fish out the chestnut kernels and rinse the residual acid with clean water.

(4) Microwave-assisted vacuum osmosis: get 13kg sucrose, 8kg xylitol, 28kg fructose syrup (29.8% fructose content, about 71% soluble solids), add water to prepare 100kg sugar solution for osmosis. According to the ratio of 3.5 kg of sugar solution per kg of chestnut kernels, the chestnut kernels were immersed in the sugar solution, and then soaked in sugar for 100 seconds under the conditions of a microwave power density of 4.5W/g chestnut kernels and a vacuum of 0.090MPa. Continue to infiltrate sugar for 60 minutes after the microwave radiation stops.

(5) Sectional drying: take out the chestnut kernels that have been soaked in sugar, drain the sugar solution, and dry them for 18 minutes under the condition of microwave power density of 2W/g chestnut kernels, and then use hot air at 80°C to dry them for 100 minutes. Quickly cooled to below 40°C, it is low-sugar preserved chestnut. The obtained product has a total sugar content of 40% (mass fraction), a water content of 15% (mass fraction), golden color and luster, a unique aroma of chestnut, strong fragrance, elasticity, certain toughness and no stickiness.

(6) Packing: Quantitatively pack the preserved chestnuts into high-temperature-resistant cooking plastic bags.

(7) Sterilization: Under the condition of microwave power density of 2.0W/g chestnut kernels, sterilize the packaged preserved chestnuts for 120s, and then rapidly cool to room temperature, which is the finished product.

Example 2:

(1) Raw material selection: thaw the frozen chestnut kernels, and select chestnut kernels that are complete, light yellow in color, free from pests and black spots.

(2) Microwave enzyme inactivation: take the microwave power density of 6W/g chestnut kernels, heat the chestnut kernels for 4 minutes to inactivate enzymes.

(3) Acid hydrolysis treatment: according to the ratio of 4 kg of acid hydrolysis solution per kg of chestnut kernels, immerse the chestnut kernels in a hydrochloric acid solution with a concentration of 0.5% (mass fraction) at 95° C. for 60 minutes. Then fish out the chestnut kernels and rinse the residual acid with clean water.

(4) Microwave assisted vacuum osmosis: get 18kg sucrose, 12kg xylitol and 21kg fructose syrup (29.8% fructose content, about 71% soluble solids), add water to prepare 100kg sugar solution for osmosis. According to the ratio of 1.5 kg of sugar solution per kg of chestnut kernels, the chestnut kernels were immersed in the sugar solution, and then soaked in sugar for 120 seconds under the conditions of a microwave power density of 3.5W/g chestnut kernels and a vacuum of 0.095MPa. Continue to infiltrate the sugar for 50 minutes after the microwave radiation stops.

(5) Sectional drying: take out the chestnut kernels that have been soaked in sugar, drain the sugar solution, and dry them for 12 minutes under the condition of a microwave power density of 4W/g chestnut kernels, and then use hot air at 60°C to dry them for 140 minutes. Quickly cooled to below 40°C, it is low-sugar preserved chestnut. The obtained product has a total sugar content of 50% (mass fraction), water content of 12% (mass fraction), golden color, luster, chestnut-specific aroma, strong fragrance, elasticity, toughness, and non-stickiness.

(6) Packing: Quantitatively pack the preserved chestnuts into high-temperature-resistant cooking plastic bags.

(7) Sterilization: Under the condition of microwave power density of 3.5W/g chestnut kernels, sterilize the packaged preserved chestnuts for 90s, and then rapidly cool to room temperature, which is the finished product.

Example 3:

(1) Raw material selection: thaw the frozen chestnut kernels, and select chestnut kernels that are complete, light yellow in color, free from pests and black spots.

(2) Microwave enzyme inactivation: take the microwave power density of 5W/g chestnut kernels, heat the chestnut kernels for 6 minutes to inactivate enzymes.

(3) Acid hydrolysis treatment: According to the ratio of 3 kg of acid hydrolysis solution per kg of chestnut kernels, immerse chestnut kernels in a hydrochloric acid solution with a concentration of 0.8% (mass fraction) at 75° C. for 100 min. Then fish out the chestnut kernels and rinse the residual acid with clean water.

(4) Microwave assisted vacuum osmosis: get 15kg sucrose, 10kg xylitol, 25kg fructose syrup (fructose content 29.8%, soluble solids is about 71%), add water and be mixed with 100kg sugar solution for osmosis. According to the ratio of 2.5 kg of sugar solution per kg of chestnut kernels, the chestnut kernels are immersed in the sugar solution, and then soaked in sugar for 150 seconds under the conditions of a microwave power density of 3W/g chestnut kernels and a vacuum of 0.085MPa. Continue to infiltrate sugar for 70 minutes after the microwave radiation stops.

(5) Sectional drying: take out the chestnut kernels that have been infiltrated with sugar, drain the sugar solution, and dry them for 15 minutes under the condition of a microwave power density of 3W/g chestnut kernels, and then use hot air at 70°C to dry them for 120 minutes. Quickly cooled to below 40°C, it is low-sugar preserved chestnut. The obtained product has a total sugar content of 45% (mass fraction), a water content of 13% (mass fraction), golden color and luster, a unique aroma of chestnut, strong fragrance, elasticity, certain toughness, and no stickiness.

(6) Packing: Quantitatively pack the preserved chestnuts into high-temperature-resistant cooking plastic bags.

(7) Sterilization: Under the condition of microwave power density of 2.5W/g chestnut kernels, sterilize the packaged preserved chestnuts for 100s, and then rapidly cool down to room temperature, which is the finished product.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (7)

1. the production method of a low sugar Chinese chestnut preserved fruit is characterized in that comprising following operating procedure:

(1) enzyme that goes out: with the Chinese chestnut benevolence heating enzyme that goes out;

(2) acidolysis is handled: the Chinese chestnut benevolence behind the enzyme that will go out immerses in the acid hydrolysis solution, floods 60～100min down at 70～95 ℃, then Chinese chestnut benevolence is pulled out, rinses residual acid solution with clear water;

(3) vacuum sugar infiltration: the Chinese chestnut benevolence that step (2) is obtained immerses vacuum sugar infiltration in the liquid glucose;

(4) drying: the Chinese chestnut benevolence that step (3) obtains is pulled out, and draining sugar liquid is dry;

(5) sterilization: the Chinese chestnut benevolence sterilization with step (4) obtains is low sugar Chinese chestnut preserved fruit;

Acid hydrolysis solution in the said step (2) is the hydrochloric acid solution of mass concentration 0.5～1.5%, and every kg Chinese chestnut benevolence needs 2～4kg acid hydrolysis solution;

Liquid glucose component in the said step (3) is sucrose, xylitol, HFCS and water; Contain 13～18kg sucrose, 8～12kg xylitol, 21～28kg HFCS in every 100kg liquid glucose; Wherein the fructose mass concentration is 29.8% in the HFCS; Soluble solid is 71%, and every kg Chinese chestnut benevolence needs 1.5～3.5kg liquid glucose.

2. according to the production method of the said a kind of low sugar Chinese chestnut preserved fruit of claim 1, it is characterized in that: the heating enzyme inactivating method in the said step (1) is heating Chinese chestnut benevolence 4～8min under Microwave Power Density 2～6 W/g Chinese chestnut benevolence conditions.

3. according to the production method of the said a kind of low sugar Chinese chestnut preserved fruit of claim 1, it is characterized in that: the Chinese chestnut benevolence in the said step (1) be complete, color and luster is yellowish, the Chinese chestnut benevolence of no insect pest, blackspot.

4. according to the production method of the said a kind of low sugar Chinese chestnut preserved fruit of claim 1; It is characterized in that: the vacuum sugar infiltration method in the said step (3) is oozed sugar for the microwave assisted vacuum; Under the condition of Microwave Power Density 3～4.5W/g Chinese chestnut benevolence, vacuum 0.085～0.095MPa; Dipping oozes sugar 100～150s, and the microwave radiation stops continued and oozes sugar 50～70min.

5. according to the production method of the said a kind of low sugar Chinese chestnut preserved fruit of claim 1; It is characterized in that: the drying means in the said step (4) is a stage drying; Be dry 12～18min under 2～4W/g Chinese chestnut benevolence condition in Microwave Power Density earlier; Use heated-air drying 100～140min of 60～80 ℃ then instead, be quickly cooled to then below 40 ℃.

6. according to the production method of the said a kind of low sugar Chinese chestnut preserved fruit of claim 1; It is characterized in that: method for disinfection is a microwave disinfection in the said step (5); Under Microwave Power Density 2.0～3.5W/g Chinese chestnut benevolence condition, sterilization 90～120s is cooled to room temperature then rapidly.

7. a low sugar Chinese chestnut preserved fruit is characterized in that: produced by the said method of each claim of claim 1～6.